(a) Field of the Invention
The present invention relates to an automatic soap dispensing device, particularly an automatic soap dispensing device which can be activated by a sensor to dispense liquid soap in a predetermined quantity automatically and precisely.
(b) Description of the Prior Art
Common soap dispensing devices, which are used extensively in the public places (e.g., washrooms, etc.), generally contain a bag of cleaning agent (i.e., liquid soap) in a housing, one end of which is connected to a soap-dispensing hose running through a seat. Soap dispensing devices include manual soap dispensing devices and automatic soap dispensing devices. Some manual devices, such as that disclosed in U.S. Pat. No. 4,256,242, squeeze the cleaning agent with a pressing cap, which, however, would most probably become a medium for spreading of communicable diseases since it is to be touched by all kinds of people coming and going in the public places. Some automatic soap dispensing devices, such as that disclosed in U.S. Pat. No. 5,492,247, use a photoelectric or infrared sensor to initiate a drive device which, via a reducing gear set, drives a liner rack to displace forward using a small gear. A block on the front side surface of the rack thus presses on a hose; thereby a precise volume of liquid is squeezed and dispensed. An automatic device disclosed in U.S. Pat. No. 5,105,992 has a motor to drive a contact roller set, which presses the hose to squeeze the liquid out in the fixed amount. Another automatic device under U.S. Pat. No. 4,722,372 has an eccentric wheel to drive the pressing rod which in turn presses the hose to squeeze the liquid out in the fixed amount.